1. Field of the Invention
The present invention relates to a method for manufacturing hot-rolled strips or sections from continuously cast primary material in successive work steps in a closed process chain, wherein the endless continuously cast primary material is divided after solidification into individual slab pieces of predetermined length, the slab pieces are heated in a temperature equalizing or soaking furnace to rolling temperature and are then rolled into the predetermined final dimensions, and wherein, for bridging a comparatively short interruption, for example, a ten-minute interruption of the rolling process, a slab piece obtained from the uninterrupted casting process is moved into a buffer zone of the equalizing furnace.
The present invention further relates to an arrangement for carrying out the above-described method.
2. Description of the Related Art
The manner of operation described above, i.e., the so-called compact strip production or CSP technology, constitutes a closed process chain with a corresponding closed arrangement chain from the steel mill to the finished coil.
In the above-described closed chain, the casting machine and the rolling mill are directly connected to each other through a temperature equalizing furnace. Oscillating shears are arranged in front of the equalizing furnace for cutting the strips emerging from the casting machine at a speed of, for example, 5.4 m/min to a length corresponding to a predetermined strip weight, for example, a length of 50 m. The strip piece then travels at casting speed through the heating zone of the equalizing furnace and subsequently through the equalizing zone of the equalizing furnace at casting speed or conveying speed in accordance with the given requirements.
The strip is accelerated from the equalizing zone to the speed of the initial pass in the finishing train. The strip then travels at this speed as required through a high-pressure descaling unit and enters a first stand of the rolling mill train.
Any problem in one of the members of this chain results in production losses and possibly even in casting stoppage. For this reason, so-called buffers are provided in the event that problems occur. For example, the equalizing furnace was extended by a buffer zone or a trouble period of up to 10 minutes of casting capacities. In the event of an assumed casting speed of 5.5. m/min, this results in an additional furnace portion having a length of about 55 m. However, when the trouble period is exceeded, this inevitably leads to casting stoppage with the attendant disadvantageous consequences. A further extension of the equalizing furnace is economically not acceptable because, on the one hand, the space required by the entire arrangement and correspondingly the costs for the arrangement increase and, on the other hand, the investment costs for the furnace itself would exceed an amount which would no longer be economically acceptable. In addition, a further extension of the equalizing furnace would mean that unoccupied storage sections of the furnace would also have to be heated during normal operation, so that the energy requirements would reach uneconomical levels.